Explanation:
Earth is not alone. It orbits the Sun with a small companion:
Asteroid 3753.
First discovered in 1986 and designated 1986 OT, this five kilometer
rock was recently found to orbit the
Sun while executing a
strange dance with the
Earth. A portion of the asteroid's
complex
orbit is shown above. As the Earth orbits once,
Asteroid 3753 follows the yellow line - while also orbiting the Sun.
Each time around, however, the yellow kidney-bean traced by
Asteroid 3753 shifts slightly - eventually
going from trailing the Earth to leading the Earth.
Every 385 years the cycle repeats.
Because the plane of 3753's orbit is tilted when compared
to the Earth's orbit, the
two will never collide. In autumn 1997,
Asteroid 3753 will pass below the
Earth's South Pole at about
100 times the distance to the
Moon. It will, however, be very
faint - about 15th
magnitude - 10,000 times fainter than the dimmest star without
a telescope.
Suggestions
are being taken for a good name for this asteroid.